CLAUDE, ALBERT

Claude had a lifelong interest in cancer research. Starting with investigations into the causes of cancer, he revolutionized the cytology of his time. By adapting and developing the most advanced biophysical and biochemical methods, such as differential high speed centrifugation, electron microscopy, and enzyme mapping, Claude characterized a class of small cytoplasmic particles, the microsomes, demonstrating that cells are endowed with a pervasive network of membranes, the endoplasmic reticulum. Eventually, microsomes were found to consist of chunks of this reticulum with even smaller particles attached to them, which came to be called ribosomes. Claude was the first to visualize the Rous sarcoma virus by means of electron microscopy. Later in his life, he turned his interest to the characterization of the cellular Golgi apparatus. In 1974, together with Christian de Duve and George E. Palade, he was awarded the Nobel Prize in Physiology or Medicine for his achievements in exploring the ultrastructure of the cell.

Origin and Early Years . Albert Claude was born in 1899 (according to his autobiography, but 1898 according to the civil register) in Longlier, a little village of the Belgian Ardennes, in the province of Luxembourg. He was the youngest of four children; he had two brothers and one sister. His father, Valentin Claude, was a baker by training. His mother, Glaudicine Watriquant, developed breast cancer when Albert was three years old. He closely experienced the inexorable progress of her illness; she died when he was seven. Other than this tragic event, his childhood was marked by the peaceful surroundings of the woods and pastures of the Ardennes. He spent his first school years at the primary school in Longlier. The school accommodated some forty children of mixed age in one room under a single teacher. In his autobiography— quipping at his own achievements—Claude praised this “pluralistic system” as “excellent.” A few years after his mother’s death, Claude and his family moved to Athus, a steel-mill region in a corner of Belgium between France and the Grand Duchy of Luxembourg. There, Albert went to a German-language school for a couple of years before being called back to Longlier to help with the care of an uncle paralyzed by a cerebral hemorrhage. With that, his formal education came to an end. He never attended a secondary school. When World War I broke out, he became an apprentice and subsequently earned his living as an industrial designer. As a patriotically minded young Belgian, Claude worked in the résistance and also for the British Intelligence Service. When the war was over, he was decorated for his courage.

Claude’s dream had always been to study medicine. However, he lacked the high school diploma that would have documented the required skills, particularly in Greek and Latin. So he decided to prepare to enter the School of Mining in Liège. But when the noted biochemist Marcel Florkin became head of the Direction of Higher Education in Belgium’s Ministry of Public Instruction for a short period, a law was passed that allowed veterans to

enter the university without the high school diploma and further examinations. Claude immediately seized the opportunity and registered, in 1922, with the Faculty of Medicine at the University of Liège. In his spare time, he frequented the laboratory of his zoology professor Désiré Damas, and later, in the course of his clinical studies, the physiological laboratory of Henri Fredericq. It was there also that he came in contact with Florkin. In the course of these formative years, he occupied himself intensely with observing cells through the microscope, gazing at “the mysterious ground substance where the secret mechanisms of cell life might be found,” as he expressed it in his Nobel Lecture, “The Coming Age of the Cell.” He also tried to isolate the eosinophilic granules of leukocytes, but failed. In 1928 Claude received his doctoral degree.

For his doctorate, he had worked on the transplantation of mouse cancers into rats. This work on heterologous transplants earned him a travel fellowship from the Belgian government. Claude decided to spend a postdoctoral year in Berlin. In Ferdinand Blumenthal’s Institute for Cancer Research at the University of Berlin, he took up the issue of a possible transfer of mouse mammary cancer by bacteria. After having shown that the effect must be due to a contamination of the bacterial culture by cancer

cells, Claude left the institute and went on to study the technique of tissue culture with Albert Fischer, a Danish guest scientist at the Kaiser Wilhelm Institute for Biology in Berlin-Dahlem.

At the Rockefeller Institute in New York . Back in Belgium in 1929, Claude received a fellowship from the Belgian American Educational Foundation (Commission for Relief in Belgium, CRB) for a research stay in the United States. He applied to the Rockefeller Institute, and Simon Flexner accepted his proposal to work on the isolation and identification of the Rous sarcoma virus. In September 1929 he sailed from Antwerp to New York. He came to work with James Murphy, a former coworker of Peyton Rous and, at the time of Claude’s arrival in New York, head of the Pathology Laboratory at Rockefeller. Rous had speculated that his filterable agent transmitting chicken tumors might be some sort of ultrabacterium or virus. But around 1915 he left the field after fruitless efforts to find similar agents affecting mammals. Murphy and Claude now proceeded from the assumption that the tumor-causing agent might be an endogenous cellular component, perhaps an enzyme of sorts, which had “gone wild” for some unknown reason. For several years, Claude attempted to isolate, enrich, and characterize Rous’s chicken tumor I agent by traditional biochemical means of aluminum hydroxide adsorption and gelatin precipitation, to no great avail. Around 1935 it came to his attention that two British groups had sedimented the filterable agent causing avian sarcomas by means of high-speed centrifugation. Encouraged by Murphy, he switched to the new technology of differential sedimentation and, within a comparably short time, managed to enrich the tumor agent by a factor of almost 3,000. The substance he had sedimented contained, in addition to phospholipids and proteins, a nucleic acid of the ribose type.

Differential Centrifugation . At the same time, however, a new research horizon was opened by a control experiment. Claude realized that, from samples of healthy chicken embryo tissue, a sediment could be obtained that was indistinguishable in its chemical composition from the infectious sample. In his Nobel Prize report of 1974, Claude’s former coworker Keith Porter referred to this event as a classic situation characteristic of the process of research: The control becomes the real experiment. Two interpretations were possible at this point. The infectious fraction might consist predominantly of an inert material that was also present in normal cells. Despite enrichment, further chemical analysis appeared hopeless in this case. Alternatively, normal cells might contain noninfectious cellular precursors of the chicken tumor agent, and in this case, the analysis of these precursors was of paramount importance. Considering these options, Claude decided to abandon the Rous sarcoma agent and to turn his attention to the differential fractionation of healthy tissue by high-speed centrifugation.

For a long time, cytomorphology had been the domain of increasingly sophisticated microscopic observation. As cellular components, nuclei and mitochondria had been visualized in situ. Subsequently, the latter had been isolated from cells by Robert Bensley and Normand Hoerr in Chicago. The tissue of choice of a nascent in vitro cytology—with early attempts going back to Otto Warburg— became the liver. In a first analysis, Claude identified his particulate cytoplasmic fraction as precursors or fragments of mitochondria. Soon, however, he had to give up this assumption. Under appropriate buffer and centrifugation conditions, a fraction of large granules could be separated from a fraction of small granules. Claude renamed his small cytoplasmic particles microsomes. The problem was

this: They could be sedimented at high speed from a tissue homogenate, but after resuspension, they could no longer be visualized by the light microscope. Faced with this situation, Claude resorted to a remarkable and convincing trick. He subjected intact cells—liver cells of Amphiuma— to high-speed sedimentation and subsequently fixed and stained them differentially. When cut parallel to the sedimentation direction, the content of such cells appeared in layers: at the bottom, glycogen; in the middle, the nucleus and mitochondria as well as secretory granules; above them, the microsomes; and finally, the cell sap (Figure 1). The microsomal layer appeared in the color of the cytoplasmic ground substance.

When introducing differential centrifugation as a means of separating the cell into its different components (Figure 2), Claude followed what he termed a “balance sheet–quantitative analysis method.” It consisted of meticulous measurements of activity and composition of the original homogenate and of all the different fractions obtained. Tumor activity could of course no longer be used as a measure after Claude switched to the analysis of healthy tissue toward the end of the 1930s. Throughout the 1940s, Claude, together with his Rockefeller colleagues Rollin Hotchkiss, George Hogeboom, Walter Schneider and George Palade, worked hard to establish what they called “biochemical mapping.” It consisted of adapting particular quantifiable enzyme tests to measure the activities of the different fractions. Soon it turned out that major enzymes of the respiratory chain segregated with Claude’s large granule fraction that consisted of mitochondria and a class of less-well-defined secretory granules. One of the big problems of differential fractionation at the time was that these two cellular components—mitochondria and secretory granules—were barely distinguishable from each other in solution. Help came, toward the end of the 1940s, from the use of a centrifugation solution of a different composition. Instead of the usual electrolyte buffers containing various amounts of salts, Hogeboom, Schneider, and Palade found sugar solutions to be a medium in which, first, sedimented mitochondria retained the filamentous structure known from in situ staining of cells, and, second, appeared to be poor in secretory vesicles. Now, the respiratory enzymes could be mapped onto these purified mitochondria with more confidence.

Consequently, in terms of their function, the mitochondria came to be addressed by Claude as the “real power plants of the cell.” The problem, however, was that enzyme mapping did not provide any clear-cut hints as to the function of the other class of isolated cytoplasmic particles, the microsomes. They steadfastly resisted this type of biochemical characterization. Claude was well aware of the work on microsomes of his Belgian colleague Jean Brachet and his coworkers Hubert Chantrenne and Raymond Jeener, who suspected the ribonucleic acid-rich particles to be involved in protein synthesis. But Claude could not convince himself of this option and stuck to the idea that microsomes might be involved in some phase of the anaerobic pathway in cellular energy generation. Consequently, he did not engage in the in vitro analysis of protein biosynthesis that was initiated by other groups with the advent of radioactive labels such as carbon (14 C) and hydrogen (3 H) after the end of World War II.

Electron Microscopy . In 1942 Claude started to add another advanced instrument to the arsenal of his analytical procedures: He secured access to the electron microscope of the Interchemical Corporation in New York, the only instrument of that type (a Model B, from the Radio Corporation of America [RCA]) then in the city. Together with Interchemical’s electron microscopist, Ernest Fullam, Claude tried to adapt the technique for the observation of biological specimens. After three years of meticulously tuning their preparation procedures—staining, fixation, dehydration, proper support—Claude and Fullam were able to present the first pictures of isolated mitochondria. In parallel and in cooperation with Rockefeller scientist Keith Porter, Claude brought whole cells under the electron microscope. For future research on cellular ultrastructure, the correlation of in vitro and in situ

representations turned out to be essential. Tissue culture specialist Porter succeeded in growing fibroblast-like embryonic chicken cells on a glass coated with a thin plastic film. The film, together with the cells, could then be transferred to an electron microscope grid, and after staining and fixation, inserted in the instrument. At their periphery, the cells were flattened enough to be penetrated by the electron beam. Besides filamentous mitochondria, a fine-spun, lace-like network of cytoplasmic threads became visible in the body of these cells. It came to be known as endoplasmic reticulum (Figure 3).

At this point, the Rous sarcoma agent reemerged as a subject of Claude’s research. The possibility of making visible the contents of cells at a resolution of about 200 Å led Claude to pick up the thread where he had left it late in the 1930s. In 1946–1947, together with Porter and Edward Pickels, he succeeded in preparing sarcoma cells for electron microscopy. It turned out that they were crammed with small, electron-dense particles (Figure 4). Nothing of that sort could be seen in healthy control cells. Thus, for the first time, the chicken tumor agent had been rendered visible and its viral nature strongly corroborated.

During the academic year 1947–1948, Claude was invited to deliver one of the prestigious Harvey Lectures under the auspices of the Harvey Society in New York. He opened the lecture with a homage to the nineteenth-century Italian astronomer and lens-maker Giovanni Battista Amici. “In the history of cytology,” he concluded, “it is repeatedly found that further advance had to await, as in the case just mentioned, the accident of technical progress” (Claude, 1950, p. 121). With this reference to Amici, Claude articulated his own research philosophy. For him, methods and results had to be equally emphasized. And indeed, he was a master in taking advantage of the “accident of technical progress” and using it to shape a new experimental cytology. To begin with, the in vitro fractionation approach to the cell met with fierce objection from many a traditional cytologist and morphologist who did not believe that valuable knowledge would be likely to result from the creation of what they called, as Brachet remembers, a “cellular mayonnaise.” But Claude was convinced of the analytical power of penetrating the ultrastructure of the cell and assigning particular functions to particular cellular compartments.

Back in Belgium: The Institut Jules Bordet . In 1946, while spending a research year in the United States, Brachet visited Claude in New York and asked him, in the name of the rector of the Free University of Brussels, whether he would be willing to come back to Belgium and join the Faculty of Medicine at the University of Brussels. Claude hesitated. It was four years before he finally agreed to leave the Rockefeller Institute, where he had spent the two most important decades of his research career. In 1950 he was entrusted with the scientific direction of the Institut Jules Bordet, the cancer research center in Brussels. He soon regretted having left New York, where he had assumed U.S. citizenship in 1941, and where he had been living with his only daughter Philippa after his divorce from his wife Julia Gilder whom he had married in 1935. To Brachet, he once confessed briefly, but clearly: “It was a mistake.” Despite the frictions in his new academic environment, Claude worked hard to modernize and develop cancer research at the University of Brussels between 1950 and 1970. For himself, he created a modern laboratory for experimental cytology and oncology in order to pursue the analysis of cellular ultrastructure. There, he engaged in research on the Golgi apparatus, whose existence had been corroborated by the electron microscope, but whose function remained enigmatic. He was able to show that the Golgi membranes are

continuous with the endoplasmic reticulum, that they are perpetually turned over and regenerated, and that in the liver cell, they are essentially involved in lipoprotein packaging and transport. Besides working on the Golgi, he continued to refine the techniques of electron microscopic specimen preparation, together with his collaborator and eventual successor at the Institut Jules Bordet, Jànos Frühling.

Louvain-la-Neuve and the Nobel Prize . After retiring in 1971, at the age of seventy-two, from the University of Brussels and from the directorship of the Institut Jules Bordet, Claude continued his laboratory work at the Catholic University of Louvain-la-Neuve, where he was invited to become professor and was given a laboratory for cell biology and oncology in 1972. There, he continued to work quietly on the ultrastructure of the Golgi complex. In 1974, together with Christian de Duve from the University of Louvain and the Rockefeller University and George Palade, from Rockefeller as well, Claude received the Nobel Prize in Physiology or Medicine for his discoveries concerning “the structural and functional organization of the cell.” Before that, he had received the Baron Holvoet Prize of the Fonds National de la Recherche Scientifique of Belgium (1965), the Louisa Gross Horwitz Prize of Columbia University in New York (1970), and the Paul Ehrlich and Ludwig Darmstaedter Prize (1971), as well as honorary doctorates from the Universities of Modena, Brno, Liège, Louvain, Gent, and the Rockefeller University. All these honors did not distract him from continuing the experimental work that he steadfastly pursued until he died, at his home in Brussels, in 1983.

Those who knew Albert Claude personally report that he was an individualist with slightly eccentric manners. Among his friends were painters, including Diego Rivera and Paul Delvaux, and musicians such as Edgard Varèse. He was, according to his colleague Brachet, a man full of contrasts. He could ask questions that scared his interlocutors. Despite his eccentricity, however, he engaged in fruitful scientific collaborations. Claude therefore can rightfully be called the pioneer of modern, interdisciplinary experimental cytology.

BIBLIOGRAPHY

A complete bibliography is included in the article by Jean Brachet, cited below.

“Growth and Differentiation of Cytoplasmic Membranes in the Course of Lipoprotein Granule Synthesis in the Hepatic Cell: 1. Elaboration of Elements of the Golgi Complex.” Journal of Cell Biology 47 (1970): 745–766.

Palade, George Emil

The Columbia Encyclopedia, 6th ed.

Copyright The Columbia University Press

George Emil Palade (pälä´dē), 1912–2008, American cell biologist, b. Iaşi, Romania, M.D. Univ. of Bucharest, 1940. He was a faculty member at the Rockefeller Institute (now Rockefeller Univ.) from 1946 to 1973, when he joined the Yale Medical School. From 1990 until 2001, when he retired, he was at the Univ. of California, San Diego, where he was the medical school's dean for scientific affairs. in Palade received the 1974 Nobel Prize in physiology or medicine with Albert Claude and Christian de Duve for contributing to knowledge about the structural and functional organization of the cell. He combined two techniques pioneered by Claude for biological applications—electron microscopy and differential centrifugation—to discover basic morphological information about ribosomes and other elements of cell biology. Palade's work led to an understanding of the cell as a sophisticated system rather than a collection of components whose functions were unknown.

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Claude, Albert

The Columbia Encyclopedia, 6th ed.

Copyright The Columbia University Press

Albert Claude (älbârr´ klōd), 1899–1983, Belgian biologist, b. Longlier, M.D., Univ. of Liège, 1928. He joined the Rockefeller Institute (now Rockefeller Univ.) in 1929 and spent his entire career there. During the 1930s and 40s, Claude did pioneering work in the use of the electron microscope to study animal cells. He also contributed to the development of differential centrifugation, a technique in which tissues or cells are homogenized and the various cell components then separated out. The techniques yielded new information about cell structure and function (Claude discovered cell mitochondria, for example), and laid the foundation for the modern discipline of cell biology. Claude was co-recipient of the 1974 Nobel Prize in physiology or medicine with Christian de Duve and George Palade for their discoveries concerning the structural and functional organization of the cell.

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